To tin a wire, strip about 3/8" of insulation from the desired wire,
twist the strands of exposed wire together, and apply a small amount
of solder so it flows between the strands of wire. The tinned wire
should not be noticeably larger in diameter than the bare wires, and there
should not be any "blobs" or "spikes" of solder. Practice on extra
wire till you get the hang of it. The shape of each individual strand should be visible through the solder, and no exposed copper should be visible.